Texas Instruments bq25570 User Manual
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Texas Instruments bq25570 User Manual

Battery charger evaluation module for energy harvesting
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User's Guide for bq25570 Battery Charger Evaluation
This user's guide describes the bq25570 evaluation module (EVM), how to perform a stand-alone
evaluation and how to allow the EVM to interface with the system and host. The boost charger output is
configured to deliver up to 4.2-V maximum voltage to its output, VSTOR, using external resistors. This
voltage will be applied to the storage element as long as the storage element voltage at VBAT is above
the internally programmed undervoltage of 2.0 V. The integrated buck converter provides up to 1.8 V and
100 mA at VOUT. The VBAT_OK indicator toggles high when VSTOR ramps up to 3.0 V and toggles low
when VSTOR ramps down to 2.8 V.
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1.2
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4.2
EVM Board Layout
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EVM Schematic
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50-mA Load Transient on V
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10
Buck Operational Waveforms During 50-mA Load Transient
11
Test Setup for Charging a Super Capacitor from Buck Output
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I/O Connections and Configuration for Evaluation of bq25570 EVM
2
SLUUAA7A - July 2013 - Revised August 2014
Submit Documentation Feedback
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User's Guide for bq25570 Battery Charger Evaluation Module for Energy
Copyright © 2013-2014, Texas Instruments Incorporated
SLUUAA7A - July 2013 - Revised August 2014
Module for Energy Harvesting
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List of Tables
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User's Guide
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Harvesting

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Summary of Contents for Texas Instruments bq25570

  • Page 1: Table Of Contents

    User's Guide for bq25570 Battery Charger Evaluation Module for Energy Harvesting This user’s guide describes the bq25570 evaluation module (EVM), how to perform a stand-alone evaluation and how to allow the EVM to interface with the system and host. The boost charger output is configured to deliver up to 4.2-V maximum voltage to its output, VSTOR, using external resistors.

  • Page 2: Introduction

    (MPPT) sampling network to optimize the transfer of power into the device. The bq25570 periodically samples the open circuit input voltage every 16 seconds by disabling the boost converter for 256 ms and stores the programmed MPP ratio of the OC voltage on the external reference capacitor (C2) at VREF_SAMP.

  • Page 3: Design And Evaluation Considerations

    (VBAT_UV) and user programmed over-voltage (VBAT_OV) levels. To further assist users in the strict management of their energy budgets, the bq25570 toggles a user programmable battery good flag (VBAT_OK), checked every 64 ms, to signal the microprocessor when the voltage on an energy storage element or capacitor has risen above (OK_HYST threshold) or dropped below (OK_PROG threshold) a pre-set critical level.

  • Page 4: Evm Schematic

    5.76M 8.66M 5.36M VSTOR VSTOR VOUT_EN Not Installed Figure 1. EVM Schematic User's Guide for bq25570 Battery Charger Evaluation Module for Energy SLUUAA7A – July 2013 – Revised August 2014 Harvesting Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated...

  • Page 5: Evm I/O Connections

    Introduction www.ti.com EVM I/O Connections Table 1. I/O Connections and Configuration for Evaluation of bq25570 EVM Headers and Description Comments/Recommended Setting Terminals J1–VIN Input source (+) If VIN_DC is higher than VSTOR and VSTOR is equal to VBAT_OV, the input VIN_DC is pulled to ground through a small resistance to stop further charging of the attached battery or capacitor.
  • Page 6 Introduction www.ti.com Table 1. I/O Connections and Configuration for Evaluation of bq25570 EVM (continued) Headers and Description Comments/Recommended Setting Terminals JP4 - VOC_SAMP VOC_SAMP = 80% configures the IC to regulate VIN to JP4 = 80% (NOTE: Do not install if JP1 shunt is installed) 80% of OCV.

  • Page 7: Evm Performance Specification Summary

    VIN_DC droops to the MPPT's sampled voltage that is stored at VREF_SAMP. SLUUAA7A – July 2013 – Revised August 2014 User's Guide for bq25570 Battery Charger Evaluation Module for Energy Harvesting Submit Documentation Feedback...

  • Page 8: Test Setups And Results

    2. VSTOR was connected a Keithley 2420 source-meter configured as a voltage source set to the VSTOR voltage. The current sunk by the source-meter was the output current of the charger User's Guide for bq25570 Battery Charger Evaluation Module for Energy SLUUAA7A – July 2013 – Revised August 2014...

  • Page 9: Test Setup For Measuring Boost Charger Efficiency

    0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 Input Voltage (V) Figure 3. Charger Efficiency versus Input Voltage SLUUAA7A – July 2013 – Revised August 2014 User's Guide for bq25570 Battery Charger Evaluation Module for Energy Harvesting Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated...

  • Page 10: Charger Efficiency Versus Input Current

    ≤ 10 X the expected current for best accuracy.) The voltage meter measured the VOUT voltage as close to the IC VOUT pin as possible User's Guide for bq25570 Battery Charger Evaluation Module for Energy SLUUAA7A – July 2013 – Revised August 2014...

  • Page 11: Test Setup For Measuring Buck Converter Efficiency

    OUT can be configured as either a current source that sinks current (i.e., negative current) or as a voltage source with voltage at least 100 mV below the lowest expected regulation voltage point. SLUUAA7A – July 2013 – Revised August 2014 User's Guide for bq25570 Battery Charger Evaluation Module for Energy Harvesting Submit Documentation Feedback...

  • Page 12: Test Setup For Performing Load Transient On Buck Output

    2.0V Figure 7. Test Setup for Performing Load Transient on Buck Output Figure 8. 50-mA Load Transient on V User's Guide for bq25570 Battery Charger Evaluation Module for Energy SLUUAA7A – July 2013 – Revised August 2014 Harvesting Submit Documentation Feedback...

  • Page 13: Charger Operational Waveforms During 50-Ma Load Transient

    TP1 and TP2. Figure 9. Charger Operational Waveforms During 50-mA Load Transient SLUUAA7A – July 2013 – Revised August 2014 User's Guide for bq25570 Battery Charger Evaluation Module for Energy Harvesting Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated...
  • Page 14 4. The LBUCK pin's ripple voltage (switching node of the buck converter) was measured by a oscilloscope voltage probe connected to TP3. Figure 10. Buck Operational Waveforms During 50-mA Load Transient User's Guide for bq25570 Battery Charger Evaluation Module for Energy SLUUAA7A – July 2013 – Revised August 2014 Harvesting Submit Documentation Feedback Copyright ©...

  • Page 15: Charging A Super Cap From

    Tips for other Tests and Measurements SLUUAA7A – July 2013 – Revised August 2014 User's Guide for bq25570 Battery Charger Evaluation Module for Energy Harvesting Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated...
  • Page 16 No other connections should be made to the EVM and the measurement should be taken after steady state conditions are reached (may take a few minutes). The reading should be much less than 100 User's Guide for bq25570 Battery Charger Evaluation Module for Energy SLUUAA7A – July 2013 – Revised August 2014...

  • Page 17: Bill Of Materials And Board Layout

    Bill of Materials and Board Layout www.ti.com Bill of Materials and Board Layout This section contains the bill of materials (BOM) and the PCB board layouts for the bq25570 EVM. Bill of Materials Table 2 lists the BOM for the EVM.

  • Page 18: Evm Pcb Top Assembly

    2013 PWR206 REV A Figure 13. EVM PCB Top Assembly Figure 14. EVM PCB Top Layer User's Guide for bq25570 Battery Charger Evaluation Module for Energy SLUUAA7A – July 2013 – Revised August 2014 Harvesting Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated...

  • Page 19: Evm Pcb Bottom Layer

    Bill of Materials and Board Layout www.ti.com Figure 15. EVM PCB Bottom Layer SLUUAA7A – July 2013 – Revised August 2014 User's Guide for bq25570 Battery Charger Evaluation Module for Energy Harvesting Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated...

  • Page 20: Pcb Layout Guideline

    Changed contents in the bill of materials NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Revision History SLUUAA7A – July 2013 – Revised August 2014 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated...
  • Page 21 ADDITIONAL TERMS AND CONDITIONS, WARNINGS, RESTRICTIONS, AND DISCLAIMERS FOR EVALUATION MODULES Texas Instruments Incorporated (TI) markets, sells, and loans all evaluation boards, kits, and/or modules (EVMs) pursuant to, and user expressly acknowledges, represents, and agrees, and takes sole responsibility and risk with respect to, the following: 1.
  • Page 22 RADIO FREQUENCY REGULATORY COMPLIANCE INFORMATION FOR EVALUATION MODULES Texas Instruments Incorporated (TI) evaluation boards, kits, and/or modules (EVMs) and/or accompanying hardware that is marketed, sold, or loaned to users may or may not be subject to radio frequency regulations in specific countries.
  • Page 23 Les types d'antenne non inclus dans cette liste, ou dont le gain est supérieur au gain maximal indiqué, sont strictement interdits pour l'exploitation de l'émetteur. Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2014, Texas Instruments Incorporated spacer Important Notice for Users of EVMs Considered “Radio Frequency Products”...
  • Page 24 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue.

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